Regulation of electric motors



' 3 Sheets-Sheet 1.

(No Model.)

w. STANLEY, Jr.

REGULATION OF ELECTRIC MOTORS.

Patented Dec. 13, 1887.

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W. STANLEY, Jr.-

REGULATION OF ELECTRIC MOTORS.

No; 374,910. Patented Dec. 13,1887.

(NO Model.) 3SheetsSh'eet 3.

, W. STANLEY, Jr.

REGULATION OF ELECTRIC MOTORS.

NO. 374,910. Patented Dec. 13, 1887.

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UNITED STATES PATENT OFFICE.

WILLIAM STANLEY, J R. OF ENGLEWOOD, NEW JERSEY, ASSIGNOR TO GEORGEWESTINGHOUSE, JR, OF PITTSBURG, PENNSYLVANIA.

REGULATION OF ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 374,910, dated December13, 1887.

(No model.)

To aZZ whom it may concern:

Be it known that I, WILLIAM STANLEY, J r., of Englewood, in the countyof Bergen and State of New Jersey, a citizen of the United States,temporarily residing at Sewickley, in the county of Allegheny and Stateof Pennsylvania, have invented or discovered certain new and usefulImprovements in Regulation of Electric Motors, of which improvements thefollowing is a specification.

In the accompanying drawings, which make part of this specification,Figure 1, Sheet 1, is a diagrammatic view of an electric motor and aregulating apparatus,i1lustrating the application of my invention when aconstant quantity of current is supplied; Fig. 2, Sheet 2, a similarview illustrating the application when a constant difference ofpotential is supplied; and Figs. 3 and 4: similar views exemplifyingmodifications in the arrangement of the demagnetizing-cireuit.

The object of my invention is to effect the regulation of an electricmotor to a determined constant speed, as may be required by the work tobe performed by the motor, so as to prevent variation of speed underincrease or diminution of duty or load.

To this end my invention, generally stated,

consists in a novel apparatus for increasing and decreasing thedevelopment of energy from an electric motor in accordance with andproportionately to variations in the work or load imposed byautomatically decreasing and increasing the electromagnetic effect of ademagnetizing-circuit upon the field-magnet of the machine, saidapparatus consisting in the combination, with an electric motor, of ademagnetizing field-circuit, a resistance line or coil, and an automaticswitch mechanism adapted to shunt a greater or less length of saidresistance-line into the demagnetizingcircuit proportionately todecrease or increase, respectively, of the work of the motor.

The improvements claimed are hereinafter fully set forth.

In the operation of electric motors it is desirable and in many casesessential to a proper and effective performance of their work that auniform speed should be maintained irrespective of the temporaryvariations in the resistance imposed by the partial cessation or theadditional imposition of work, as in the case of the illumination of agreater orless number of electric lights or the operation of more orless machinery from time to time. Motors employed in such service may beoperated under either of two different conditionsfirst, where theelectric energy actuating the motor is supplied as a constant quantityof current flowing through a line, in which case the electro-motiveforce applied to the terminals varies as the work performed, and,second, where a constant electro-motive force or difference of potentialis applied to the terminals of the motor, in which case the quantity ofcurrent flowing through the motor will be varied proportionately'withvariations in the work.

My invention, which is equally applicable under either of theabove-stated conditions, affords ready and effective means for insuringthe maintenance of such speed of the motor as may be suitable orrequisite for the performance of the particular duty to which it is assigned.

Referring first to the case of a motor adapted to use in a line suppliedwith a constant quantity of current, Fig. 1 illustrates a constructionadapted to the practice of my invention. The motor, which may be of anysuitable and preferred construction, is here shown as provided withmagnet-cores 1O 11, provided with pole-pieces 12 13, between which anarmature, 14, is adapted to rotate in the usual manner. Theelectriceurrent which actu'ates the motor passes from a generator orother suitable source of supply through an energizingcircuit composed ofa wire, 1, connected to one of the terminals, 8, a wire, 2, wound uponthe magnet-cores 10 11 and leading from the terminal 8 to one of thebrushes, 15, of the armature 14, a wire, 3, wound around a regulatingelectromagnet, 4, and extending from the other brush, 16, to theopposite terminal, 9, and a wire, 5, leading from the terminal 9 to thegenerator.

A demagnetizingcircuit, which is praetically a shunt across theterminals of the mo tor, is formed by a finer wire, 6, leading from theterminal 8, and wound around the magnet-cores 1O 11, to a connectionwith a resistance line or coil, 7, from which a series ofconnecting-wires, 17, extend at different points in 1ts length tocontact-plates 18. The demagnetizing-circuit on the opposite side of theresistance line or coil 7 extends through an automatic switch-lever, 20,pivoted at one end by a link, 23, to the armature 22 of theregulating-magnet 4, and adapted to make contact, as raised or loweredby the movements of the armature, with either of the differentcontaet-plates 1S, and wires 24 25 lead from the switch-lever 20 to theterminal 9 of the motor. The fine wire of the demagnetizing-circuit isof comparatively high resistance relatively to the coarser wire of theenergizing-circuit, and consequently takes a smaller portion of thecurrent, and when the motor is in motion the quantity of current flowingthrough the demagnetiziug-circuit is proportional to the counterelectro-motive force of the motor and the resistance of theenergizing-circuit is less than that of the demagnetizing-eircuit. \Vhenthe current is turned on the motor from the generator, the regulatingmagnet i raises the switch-lever 20 and holds it with its free endincontact with the plate 18, which is connected with the fartherextremityof the resistanceline 7, thereby throwing a maximum of resistance intothe demagnetizing-circuit until the motor has obtained through therevolutions of its armature sufficient counter electro-motive force tocause the resistance of the energizing-circuit through the wires 2 3 toexceed that of the demagnetizingeireuit through the wire 6,resistanceline 7, connection 17, contact-plate 18, switch-lever 20, andwires 24 25.

Such increase of resistance, by demagnetizing the regulating magnet 4,allows the switeL- lever 20 to fall back to the position shown in thedrawings, in which the minimum of resistance is shunted into thedemagnetizing-circuit and the demagnetizing effect of said circuit is atits maximum, such demagnetizing effect tending to reduce the counterelectro-motive force by demagnetiziug the field-magnets of the motor.If, now,aload be added,the amount of current flowing through theenergizing-circuit will be increased by reason of the decrease ofcounter electro-motive force due to the slowing up of the armature.Thisincrease of current excites the regulating magnet 4E and causes itto lift the switch-lever 20, thereby increasing the resistance of thedemagnetizingcircuit by throwing in a greater length of the resistanceline or coil 7, such increase of resistance correspondingly increasingthe speed of the motor, both by reason of the decrease of thedemagnetizing effect of the demagnetizing-circuit and of the increase ofthe magnetizing effect of the energizing-circuit, due to the arrangementof the two circuits as shunts to each other. The movement of theswitch-lever in direction to increase resistance continues until thecounter elcctro-motive force has risen sufficiently to decrease thequantity of current through the energizingcircuit, and thereby to stopthe upward pull of the magnet. If, on the other hand, the mechanicalloadbe decreased, the revolutions of the armature will be momentarilyincreased, the counter eleetro-motive force will be increased, and theregulating-magnet 4 will thereby be weakened. The resistance of thedemagnetizingcircuit will consequently be decreased by the lowering ofthe switchlever, and a greater quantity of current be permitted to flowthrough said circuit, such increase of current demagnetizing the magnetsof the motor and reducing its speed to the degree required.

Fig. 2 illustrates a construction applicable in cases where a constantdifference of potential between the terminals 8 9 of the motor is employed. The current of the energizing-circuit passes through the wire 1to the terminal 8 of the motor, thence through the wire 2, wound uponthe magnet-cores 1O 11, to one of the brushes, 15, and from the otherbrush, 16, through a wire, 3, wound upon the regulatingmagnet 4, to aconnection, 26, at which it is di vided, a portion passing through ademagnet izing-circuit composed of a wire, 27, leading to abinding-post, 28, on the motor, anda wire, 6, leading from thebinding-post 28 to the terminal 9 and wound upon the magnet-cores 10 11.The other portion of the current passes as a shunt to this circuit,having a variable resistance formed by the wire 29, switch-lever 20,contact-plates 18, connections 17, resistance line or coil 7, and wire30.

WVhen current is not turned on to the motor, the armature of theregulating magnet not being attracted,the connected end ot'theswitchlever is in its lowest position, as shown in the drawings, andconsequently the maximum rcsistanceisthrownintotheshunt-circuit.- Uponthe application of a current to the motor the regulating-magnet 4, beingexcited, lifts the switch-lever 20, and by cutting out a portion of thevariable resistance allows a greater quantity of current to flow throughthe shunt circuitwires 29 30 to the terminal 5 and aless quantitythrough the demagnetizirig-circuit, and the motor consequentlyincreasesits speed until the counter electro-motive force rises sufficientl y toreduce the strength of the regulating-magnet and increase the resistanceof the shunt-circuit to the required degree. Under such construction thestrengthening of the regulating-magnet cuts out resistance in lieu ofthrowing in resistance, as in' the case first described; but in both thesame rcsult--to wit, the reduction of the effect of thedemagnetizing-circuit-is attained by the strengthening of the magnet.

It will be obvious that the arrangement of circuits may be modified insundry particulars without departing from the spirit of my invention, solong as a regulating-magnet and variable resistance are employed to varythe field strength of a motor by varying thestrength YOU counterelectro-motive force of the armature is highest, while in theconstruction shown in Figs. 1 and 2 the magnetic strength of theregulating-magnet decreases when the counter electro-motive forceishighest. Again,in Fig. 3 the upward movement of the armature of theregulating-magnet decreases the variable resistance, while in Fig. 1 theupward movement of said armature increases the variable resistance.

The specific regulating mechanism herein 3 shown does not per seconstitute part of my present invention, and need not therefore be atlength described, as other devices may be equivalently employed in thepractice of my invention to attain the result effected thereby. Saidmechanism, moreover, constitutes the subject-matter of anotherapplication for Letters Patent filed by me of even date herewith.

In lieu of employing a demagnetizing-coil, as hereinbefore described,the same may be omitted and thefield strength of the motor may be variedby simple shunts around the field-magnet coils; or the field-coilsresistance mayitselfbevaried. Such arrangements,however, differ frommyinvention in the essential particular that all the energy expended inthe circuits by which the field-coils resistance is varied is lost,While the energy exerted in a demagnetizingcoil affects the motor in asimilar manner to that of a generator, tending to advance the directionof the current; or, more simply, the result of the effect of theenergizing and demagnetizing coils in the motor is such as would beproduced by a generator and a motor combined in one machine, thegenerator acting as a brake to the motor. Regulation may further beeffected under my invention with the employment ofa comparatively smallresistance, which is particularly desirable in dealing with currents ofgreat intensity.

resistance in said circuit coincidently with and proportionately tovariations in the mechanical duty of 1 the motor, substantially ashereinabove set forth, is not herein claimed, as the same willconstitute the subj cot-matter of a separate application for LettersPatent by me.

I claim herein as my invention- 1. In an electric motor, the combinationof an energizing field-circuit, a demagnetizing field-circuit, avariableresistance located therein as a shunt around a regulating-magnetwhose strength is controlled by the counter electromotive force, and anautomatic switch mechanism actuated by said magnet to increase ordecrease the quantity of resistance in the demagnetizing field circuitby Variations 1n counter electro-motive force effected by variations inthe speed of the motor, substantially as set forth.

2. In an electric motor, the combination of a shunt-circuit around theterminals of the motor, a demagnetizing-coil upon thefieldmagnet of themotor and included in said circ'uit, a regulating-magnet, a variableresistance in a shunt around the regulating-magnet, and an automaticswitch mechanism actuated by the regulating-magnet to shunt a greater orless proportion of said resistance into the circuit of thedemagnetizing-coil in inverse proportion to the counter electro-motiveforce of the motor, substantially as set forth.

3. In an electric motor, the combination of a main or energizingcircuit, a regulatingmagnet in said circuit, a shunt-circuit to themotor, including a demagnetizing field-coil, a variable resistance, andan automatic switch mechanism operated by the regulating-magnet to varythe amount of resistance in the demagnetizing-coil inversely as thecounter electromotive force and speed of the motor, to the end ofmaintaining a constant determined speed thereof, substantially as setforth.

In testimony whereof I have hereunto set my hand.

\VILLIAM STANLEY, JR. \Vitnesscs:

J. SNowDEN BELL, F. O. MILLER.

